Assessing Oxaliplatin-Induced Nausea and Vomiting in Mice

The behavioural phenomena of oxaliplatin-induced nausea and vomiting were evaluated via measurement of the pica response. Mice do not vomit but show an equivalent measurable behaviour called pica, defined as eating non-food items such as bedding material. Thus, pica is an indirect marker of emesis that was measured by the ingestion of kaolin clay (a non-nutritive substance). Mice ingest kaolin as an innate curative response for GI disturbances. Oxaliplatin-induced pica was quantified by measuring the consumption of kaolin pellets. Kaolin pellets were prepared as previously described [14 (link),15 (link)]. Briefly, kaolin (hydrated aluminum silicate; 98.5%) was mixed with 0.5% carmine and 1% gum Arabic to form a thick paste. The paste was then processed such that the shape and size of the kaolin pellets resembled that of the normal laboratory mouse food pellets.
After three days of acclimatization to the presence of kaolin (day 0), mice received i.p. injections either of oxaliplatin or saline, with kaolin and normal feed given immediately after i.p. injections. The amount of kaolin versus food intake was measured daily to observe the presence of abnormal eating patterns. Feces were collected at 0, 3, 7, and 14 days. After collection, fecal samples were counted and homogenised to determine the carmine concentration at absorbances of 550 and 700 nm using a spectrophotometer (PharmaSpec UV1700, Shimadzu, Japan).